Stem cells can be proliferated or expanded and differentiated into many different cell types, primarily depending upon the type and source of the initial stem cell. Stem cells are of high interest to the research community and regenerative industry because of these features. In particular the ability to expand the population and direct differentiation has led to intense study of stem cells for the purpose of supplying cells and tissues to cure human diseases.
Human pluripotent stem cells are currently being proliferated and directed to differentiate into specific lineages, particularly for the development of therapeutic objectives. In addition, they are very useful scientific tools for the study of cellular processes and differentiation.
Basic techniques for culturing human cells have been described, but there are limitations and drawbacks to many of the procedures currently used. For example, mouse embryonic fibroblast feeder cells have been used to culture human ES cells. Likewise, conditioned medium using bovine collagen as a base layer has been used to grow stem cells. However, the growth of stem cells on non-human feeder cells and the use of conditioned media raise concerns that one or more agents, such as a virus, could be introduced into the cells and subsequently transmitted to a patient.
Cells can be cultured on a collagen support, however if those cells are to be transplanted into a human subject that collagen support should be human collagen.
Collagen is used as an implant material to replace or augment hard or soft connective tissue, such as skin, tendons, cartilage, and bone. Some implants are formed as solid, flexible, or deformable collagen masses cross-linked with chemical agents, radiation, or other means to improve mechanical properties, decrease the chance of an immunogenic response, and/or to manage the resorption rate, or to improve the mechanical properties.
Collagen-based medical implants for use in humans generally have been of a non-human origin, i.e., xenogenic. A problem with the use of xenogenic tissue as a starting material when generating medical implants is that the tissue may be contaminated with viruses or prions. For example, products using bovine sourced tissue have the potential for transmitting BSE (Bovine Spongiform Encephalopathy).
Another problem with the use of xenogenic tissue is the potential for inflammation responses, hematomas, adhesions, and rejection after implantation. This is because xenogenic collagen and telopeptides can include antigens and other constituents that can initiate an immunogenic response in humans. Additionally, a certain proportion of patients can develop allergic reactions to implanted xenogeneic materials.
Thus, there is a need for methods to isolate collagen fiber and/or thread base materials for products made from the collagen fiber and/or thread base materials that are less likely to produce an immunogenic response.
The inventor here has found an improved collagen composition that increases the growth rate of human cells. This provides both an improved matrix for growing cells and also allows the cells and matrix to be implanted into a mammalian subject.